// already using Collections.newSetFromMap and ConcurrentHashMap.
    return Collections.newSetFromMap(new ConcurrentHashMap<E, Boolean>());
  }

  static <E> Set<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
    return Sets.newLinkedHashSetWithExpectedSize(expectedSize);
  }

  /**
   * Returns the platform preferred map implementation that preserves insertion order when used only
   * for insertions.
   */

  }

  /**
   * Returns the platform preferred implementation of an insertion ordered set based on a hash
   * table.
   */
  static <E extends @Nullable Object> Set<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
    return CompactLinkedHashSet.createWithExpectedSize(expectedSize);
  }

  /**
   * Returns the platform preferred map implementation that preserves insertion order when used only

  }

  public void testNewLinkedHashSetWithExpectedSizeSmall() {
    LinkedHashSet<Integer> set = Sets.newLinkedHashSetWithExpectedSize(0);
    verifySetContents(set, EMPTY_COLLECTION);
  }

  public void testNewLinkedHashSetWithExpectedSizeLarge() {
    LinkedHashSet<Integer> set = Sets.newLinkedHashSetWithExpectedSize(1000);
    verifySetContents(set, EMPTY_COLLECTION);
  }

  public void testNewTreeSetEmpty() {

      this.expectedValuesPerKey = checkNonnegative(expectedValuesPerKey, "expectedValuesPerKey");
    }

    @Override
    public Set<V> get() {
      return Platform.newLinkedHashSetWithExpectedSize(expectedValuesPerKey);
    }
  }

  private static final class TreeSetSupplier<V extends @Nullable Object>
      implements Supplier<SortedSet<V>>, Serializable {

  }

  public void testNewLinkedHashSetWithExpectedSizeSmall() {
    LinkedHashSet<Integer> set = Sets.newLinkedHashSetWithExpectedSize(0);
    verifySetContents(set, EMPTY_COLLECTION);
  }

  public void testNewLinkedHashSetWithExpectedSizeLarge() {
    LinkedHashSet<Integer> set = Sets.newLinkedHashSetWithExpectedSize(1000);
    verifySetContents(set, EMPTY_COLLECTION);
  }

  public void testNewTreeSetEmpty() {

   *
   * @return a new {@code LinkedHashSet} containing a collection of values for one key
   */
  @Override
  Set<V> createCollection() {
    return Platform.newLinkedHashSetWithExpectedSize(valueSetCapacity);
  }

  /**
   * {@inheritDoc}
   *
   * <p>Creates a decorated insertion-ordered set that also keeps track of the order in which
   * key-value pairs are added to the multimap.

   *     elements without resizing
   * @throws IllegalArgumentException if {@code expectedSize} is negative
   * @since 11.0
   */
  public static <E extends @Nullable Object> LinkedHashSet<E> newLinkedHashSetWithExpectedSize(
      int expectedSize) {
    return new LinkedHashSet<>(Maps.capacity(expectedSize));
  }

  // TreeSet

  /**